1. Field of the Invention
The present invention relates to a socket for testing non-defective or defective of an IC package manufactured.
2. Description of the Prior Art
Sockets of various constructions have been proposed which are provided with a plurality of contact members detachable to contacts of an IC package, mounted on a base member, whereby pushing down a desirable member can move the contact members outward so as to detach the IC package without a load.
There has been disclosed a socket for IC inspection, for example, in the Japanese Patent Laid-open No. Sho 63-299257, which is provided with contact pins having a base inserted into the socket body, movable pieces extending out from the base through an elastic curvature, and contact pieces branching out in the opposite direction from the movable pieces and pressing lead terminals by elasticity of the elastic curvature, and release means being in contact with the movable pieces and capable of releasing the contact pieces from pressing the lead terminals.
As another example, a socket for testing IC devices has been disclosed in the Japanese Patent Publication No. Hei 4-12624, which is provided with a clamp swingable between a closed position adjoining to an upper side of a base and an open position extending outward on the upper side of the base, an energizing member for energizing the clamp to the closed position, and contacts attached on the clamp, laterally extending.
A socket assembly has been disclosed in the Japanese Patent Laid-open No. Hei 5-152392, which is provided with arms that have a plurality of contact elements disposed along two arms of a support flame and can be swung vertically as means to move contact parts with IC devices in the contact elements, and cam members that have cam projections for giving outward forces to the contact elements.
However, a detailed examination of the foregoing conventional sockets will reveal the following problems.
In case of the construction as disclosed in Japanese Patent Laid-open No. Sho 63-299257, the contact piece a of the contact pin slidingly comes into contact with the lead terminal b while moving from the outward part of the lead terminal b to the inward part thereof.
In other words, the contact piece a goes upward on the slope b1 in the bent area of the lead terminal b and increases scratches, which will lead to scrape a surface plating on the lead terminal b and will easily produce plating scraps c. The plating scraps will fall down and remain on a base d on which the lead terminal b is mounted, and adhere to lead terminals of an IC package mounted next, which gives a possibility leading to deformations and/or electric faults of the foregoing lead terminals (refer to FIG. 12).
The socket according to the Japanese Patent Publication No. Hei 4-12624 has a construction in which the contact moves virtually horizontally to slidingly come into contact with a lead of an IC. As the clamp moves from the open position to the closed position after the IC is mounted on the upper side of the base, the contact slidingly comes into contact with the lead of the IC moving from the outside to the inside. Since the IC is set upside down, the aforementioned troubles do not occur. However, since the contact moves from the outside to the inside, a stress to press the lead of the IC inward (toward the IC body) is exerted, and consequently, a potential problem of a deformed lead remains.
In the socket according to the Japanese Patent Laid-open No. Hei 5-152392, on the other hand, the cam projection moves the contact part outward against the resiliency of the elastic part of the contact element, when the arm is swung downward. To go into the details, the cam projection swings the contact part upward, and the contact part does not slide of scrape on the lead of the IC; and therefore, plating scraps are not produced and the lead is not deformed as described above. However, an oxide film formed on the lead of the IC will exert an influence on a reliable conductivity between the contact part and the lead of the IC. Therefore, in such a construction, the contact pressure to the lead of the IC by the contact part is necessary to be increased (resiliency of the elastic part is increased), which, however, shortens the life of the contact element as well as deteriorates maneuverability to swing the arm downward.